Pregnant women who smoke 10 or more cigarettes a day, who are between the ages of 16 and 35, and who register with a private collaborating obstetrician before their 16th week of pregnancy will be randomly allocated to a treatment group who will be asked to actively participate in a smoking cessation program to quit smoking and a control group who will receive anti-smoking advice from their health providers. Mean birth weight of the two groups of infants will be compared to determine if smoking during pregnancy is a causal factor in low birth weight. The objective of the study is to demonstrate the feasibility of reducing smoking among pregnant women and to determine if maternal smoking is a causal factor in reducing the birth weight of the infant.